Influence of fly ash filler on the mechanical properties and water absorption behaviour of epoxy polymer composites reinforced with pineapple leaf fibre for biomedical applications

This study explores the impact of fly ash (FA) filler on the mechanical, morphological, and water absorption properties of pineapple leaf fibre (PALF)-reinforced epoxy composites for biomedical applications. PALF, sourced from abundant agricultural waste, offers a sustainable alternative to synthetic fibres. Employing the hand layup process, varying wt% of FA (3%, 6%, and 9%) are incorporated into PALF-reinforced epoxy composites with different PALF concentrations (10%, 20%, and 30%). Mechanical assessments, including impact, flexural, and tensile strength, reveal that the introduction of up to 6 wt% FA enhances tensile strength by 65.3%, reaching its peak at this concentration. Flexural strength also improves by 31.9% with 6 wt% FA, while impact resistance reaches its maximum (74.18% improvement) at 9 wt% FA. Water absorption measurements demonstrate a decrease with increased FA content and exposure period, indicating enhanced water resistance. Scanning electron microscopy confirms the uniform distribution of FA, contributing to improved mechanical characteristics and water resistance. Optimality tests using Taguchi and response surface methodology (RSM) further confirm the experimental outcomes, emphasizing the potential of FA to enhance natural fibre-reinforced composites. This research suggests FA as a promising filler to elevate mechanical performance and water resistance in environmentally friendly composites.


Introduction
1][12][13] Hence, the present work is a novel approach towards such an attempt.0][21][22][23] The choice of suitable bres for the fabrication of composites is also a major challenge, based on several attributes.In this regard, PALF is a discernible natural reinforcement, with excellent bonding strength that can be used as reinforcement.The use of PALF, owing to its renewable nature, costeffectiveness, and advantageous mechanical qualities, enhances the strength of the composites.
Although natural reinforcements provide eco-compatibility and enhanced sustainability, their biodegradability has affected the characteristics of the composites.9][30][31] Hybridization involves combining with other natural or synthetic llers to obtain a combination of their respective properties in the resulting composites, broadening their range of application.8][39][40][41] The addition of FA, red mud and other discernible wastes causing threats to environment, as ller materials to a polymer matrix is a novel research area, since ndings on the effectiveness of utilizing these discernible wastes from human activities are still in their nascent stage, and only incipient information is available.3][44][45][46] Inorganic llers are preferred to achieve better characteristics.The impact of llers on composite properties depends on their size, shape, aspect ratio, surface area, and dispersion within the composite. 47,48illers added to polymer matrices contribute to improved mechanical properties and reduced water absorption in brereinforced composites due to their homogenous dispersion achieved by mechanical action. 49This ensures effective stress transfer between the matrix and llers during loading, enhancing mechanical properties.However, an excessive amount of ller can lead to agglomeration and decreased bonding strength between the matrix and bres, resulting in reduced mechanical strength. 50Effective utilization of llers depends on their particle size, with smaller particles providing a higher surface area per unit weight and better interaction with the polymer matrix.Fillers offer high aspect ratios and specic surface areas, making them ideal for enhancing various properties of composites. 51nderstanding how the addition of y ash affects the mechanical properties and water absorption behavior of polymer composites can aid in developing materials suitable for biomedical devices, implants, or prosthetics.It provides insights into the durability and stability of these materials in biological environments.Composites developed by reinforcing llers through advanced manufacturing methods exhibit highperformance characteristics.Integrating nanotechnology principles into composite development can signicantly enhance overall performance.3][54] Inorganic llers include various materials like zinc oxide, alumina, calcium carbonate, and silica, while organic llers consist of particulates derived from plants and animals.The quantity of ller added to the polymer matrix depends on the type of ller and matrix used, usually varying between 4% and 5% by weight. 55Overall, llers offer great potential for improving the mechanical performance of composites and advancing innovative materials for diverse applications.Continued research in this area is crucial for the development of sustainable and high-performance composite materials.In this regard, the objectives of the present work are framed with a clear-cut focus on the development of sustainable composites making use of PALF reinforcements and FA ller material.The use of FA for the development of sustainable polymer composites provides a suitable method for utilizing the discernible by-product of the combustion of coal in thermal power plants, which is a major threat to the environment across the globe.The dumping of FA in landll is causing serious concerns with respect to soil, air and water pollution.Thus, there is a need to develop eco-compatible methods of utilizing FA to develop composites that have better characteristics and are sustainable.

Materials and methods
In this study, LY-556 epoxy/HY-951 hardener, acquired from SS Impex, Bangalore, was chosen as the matrix material.Fig. 1 gives the specic molecular structure of the epoxy and hardener used in the present work.The specic molecular structures of LY-556 epoxy resin and HY-951 hardener are proprietary and typically not publicly disclosed by the manufacturers.However, epoxy resins like LY-556 usually comprise linear polymers containing epoxide functional groups (-CH 2 -CH 2 -O-), offering versatile properties tailored to diverse applications.Conversely, hardeners such as HY-951 oen contain amine functional groups (-NH 2 ) that facilitate crosslinking with epoxy resins, leading to a robust three-dimensional network structure during curing.Epoxy resins are prized for their adhesive strength, chemical resistance, and mechanical integrity, while hardeners play a crucial role in enhancing the overall performance of the material.Though the density and other characteristics of these materials can vary widely depending on their formulation and intended use, epoxy resins typically exhibit densities ranging from 1.1 to 1.4 g cm −3 , while hardeners may fall within the range of 0.8 to 1.2 g cm −3 .
Pineapple leaf bre (PALF) chopped to ne lengths in the range of 8 mm to 12 mm with diameters in the range of 10 mm to 25 mm obtained from 'Greentech Fibres', Chennai, was used as reinforcement.The cellulose content of PALF typically ranges from 65% to 75% of its total composition.The lignin content, on the other hand, generally constitutes about 20% to 25% of PALF's composition.However, PALF bres require suitable pretreatment with silane-based coupling agents.In FA-PALFepoxy composites, coupling agents are pivotal to augment the mechanical properties through facilitating enhanced adhesion among the composite constituents.Given the disparate surface chemistries of FA, PALF, and the epoxy matrix, effective bonding necessitates intermediary compounds.Coupling agents, like silane-based varieties, serve this purpose by forming chemical bonds with the organic and inorganic components.These agents feature functional groups capable of reacting with hydroxyl groups on FA and PALF surfaces, as well as with epoxy resin molecules, thereby fostering improved compatibility.This chemical bridging enhances stress transfer across interfaces, leading to heightened mechanical properties, such as tensile and exural strength, along with increased impact resistance.
Fly ash of particulate sizes in the range of 40 mm to 75 mm sourced from the KPCL plant, Raichur, Karnataka, was further used as ller material to enhance the performance of the PALFreinforced composites.FA, rich in silicon dioxide, alumina, and iron oxide, was identied for its potential to improve mechanical and morphological properties while addressing environmental concerns related to its disposal.Through initial trials and a literature review, the weight percentages of PALF (ranging from 10% to 30%) and FA (ranging from 3% to 9%) were determined.It was found that PALF below 10 wt% led to reduced strength characteristics, while exceeding 30 wt% caused coring and agglomeration, resulting in the formation of voids.Similarly, FA content below 3 wt% had minimal impact on strength, but when it exceeded 9 wt% it led to debonding of bres due to FA agglomerates in the matrix.The experimental design followed an L9 'orthogonal array', with optimal weight percentages determined to be 20 wt% PALF and 6 wt% FA.Table 1 gives the wt% of the constituents for different composite specimens.
The composites are fabricated using ultrasonic-assisted stirring and hand layup techniques under room-temperature conditions on a dry granite slab.This process entails manually mixing chopped pineapple bres and FA with the epoxy hardener matrix through stirring.Prior to pouring the mixture into the mold, the mold surface is cleaned thoroughly and a release agent is applied to prevent sticking.Each layer is meticulously wetted with epoxy resin using brushes and rollers to ensure proper adhesion and to eliminate air pockets or voids.Layer-by-layer application continues until the desired thickness and laminate structure are achieved.Aer consolidating the layers and removing trapped air bubbles, the composite is allowed to cure according to the recommended time and temperature (24 h and 90 °C) provided by the epoxy resin manufacturer.Once fully cured, the composite part is demolded, trimmed, and nished to achieve the desired nal appearance and smoothness, following the safety precautions and guidelines outlined by the resin and hardener manufacturers.Fig. 2 depicts the DSC of epoxy curing while Fig. 3 shows a photograph of the composite laminate fabricated in this study.The DSC curve exhibits a distinct curing reaction peak occurring at 19.26 minutes.This peak indicates the onset of epoxy resin curing, marking the initiation of the crosslinking reaction between the epoxy resin and the curing agent.The corresponding heat ow observed at this peak is measured at 1193 mJ, signifying the amount of heat ow during the curing process.
The composite laminate undergoes cutting using abrasive jet machining to meet ASTM standard sizes for tensile, exural, and impact tests.Tensile tests adhere to ASTM D3039/D3039M standards, with specimens prepared with dimensions of 50.8 mm gauge length, 12.7 mm width, and 3.2 mm thickness, tested on Instron 3360 series equipment.Flexural tests follow ASTM D790/D790 M standards using 127 mm long, 12.7 mm wide, and 3.2 mm thick specimens, while Izod impact testing conforms to ASTM D256 standards with specimens of 63.5 mm  length, 12.7 mm breadth, and 3.2 mm thickness.The results are recorded and analyzed to assess the impact of FA on characteristics.Water absorption behavior is investigated according to ASTM D 570-98 standards, with rectangular samples of 75 mm length, 25 mm width, and 3.2 mm thickness subjected to pretreatment drying followed by immersion in distilled water.Weight measurements at intervals, alongside calculations using eqn (1), determine water absorption%.
where W t is the weight of the sample at time t, and W 0 is the initial weight recorded before immersion in water.
The procedure is repeated for all the composite specimens to determine the water absorption for different wt% of bre and ller contents and for different durations of time.

Results and discussion
The results presented in Table 2 give the mechanical properties of pineapple leaf bre (PALF) and FA reinforced epoxy composites with varying wt% of FA (ranging from 3 wt% to 9 wt%) and pineapple leaf bre (ranging from 10 wt% to 30 wt%).Additionally two unique combinations of neat epoxy + F6 and neat epoxy + P20 are characterized to understand the impact of unitary inclusions of FA and PALF, respectively, on the characteristics of the composites.

Ultimate tensile strength (UTS)
As the wt% of pineapple leaf bre increases beyond 20 wt%, there is a general trend of decrease in the UTS of the composites.This is likely due to the intrinsic nature of natural bres, which have lower tensile strength compared to synthetic bres or other reinforcing materials.On the other hand, the addition of FA seems to improve the UTS.Overall, the composites with higher FA content and lower pineapple leaf bre content tend to exhibit higher UTS.P20F6 exhibited the highest tensile strength, showcasing an improvement of 65.3% compared to neat epoxy.Fig. 4 gives a comparative bar chart for UTS for different wt% of PALF and FA.

Young's modulus
The results show that increasing the FA beyond 6 wt% results in a decrease in Young's modulus.This can be attributed to the fact that natural bres are generally less stiff than synthetic bres.FA, on the other hand, is observed to have a favourable impact on Young's modulus, suggesting that it functions as a reinforcing ller to increase the stiffness of the composite.Composite P20F6 has the greatest stiffness, measuring 3.6 GPa for Young's modulus.Fig. 5 gives a comparative bar chart for Young's modulus for different wt% of PALF and FA.

Flexural strength and exural modulus
Flexural strength and exural modulus are important properties in determining the ability of a composite to withstand bending or exing loads.The results indicate that increasing the wt% of pineapple leaf bre leads to a slight decrease in both exural strength and exural modulus.This is consistent with the trend observed in the UTS, where the lower strength of natural bres affects these properties.On the other hand, as seen in the UTS and Young's modulus, the addition of FA seems to have a positive effect on exural strength and exural modulus, contributing to the enhanced resistance of the composite to bending.P20F6 displayed a maximum exural strength of 165.3 MPa, demonstrating a 31.9%enhancement compared to neat epoxy.Fig. 6 and 7 give comparative bar charts for exural strength and exural modulus for different wt% of PALF and FA, respectively.

Impact strength
Impact strength measures the ability of a material to absorb energy during impact loading.Interestingly, the impact strength does not follow a consistent pattern with varying wt% of pineapple leaf bre and FA.For instance, the impact strength increases with the addition of pineapple leaf bre and FA content in the P20F3, P30F3, P10F6, P20F6, P30F6, P10F9 composites, and is a maximum for the P20F9 composite with a value of 39.68 kJ m −2 exhibiting an improvement of 74.18% compared to neat epoxy, but it decreases slightly in the P30F9 composite.Such behavior could be attributed to the complex interplay of factors like bre dispersion, interfacial adhesion, and the orientation of bres in the composite.The impact strength of composite materials is intricately linked to the uniform distribution of reinforcing bres within the matrix (bre dispersion), the strength of the bond between bres and the matrix material (interfacial adhesion), and the orientation of these bres.Enhanced impact resistance results from a more uniform bre dispersion that mitigates stress concentration, robust interfacial adhesion promoting efficient stress transfer, and a strategic bre orientation that bolsters the ability of the material to withstand impact loads.Notably, these factors are not independent but interact synergistically, and a holistic approach to optimizing these parameters can yield substantial improvements in impact resistance, rendering composite materials highly versatile for a wide array of applications. 56,57ig. 8 gives a comparative bar chart for impact strength for different wt% of PALF and FA.
Research conducted by P B Anand et al. 20 most likely included an examination of how various composite materials responded when subjected to controlled impact forces.These impact tests would have entailed applying specic levels of force to the materials and then assessing how well they resisted breaking or undergoing deformation as a result of these impacts.The outcomes of these tests are in line with the ndings of the present work, wherein the bre bonding facilitated by the pretreatment and addition of ller material endures the impact forces imposed upon it.In essence, the study aimed to evaluate the ability of the composite materials to withstand and absorb the energy from applied impact loads, and this information was likely presented through numerical data, graphs, or tables that showcased the specic impact strength values.Such results are crucial in determining the suitability of these materials for various applications where impact resistance is a signicant factor.

Test for optimality
The provided data is associated with a design experiment, where various factors and responses were measured across different trials.From the experimental trials, it is evident that the 29th trial seems to be the optimized trial for the tested factors and the objectives of the experiment.In the present  work, Design-Expert is used for designing experiments and optimizing processes by analyzing complex experimental data.
To interpret the 60th optimality run number, with 20.837 wt% PALF, and 6.46374 wt% FA, we observed optimized response variables.The test for optimality checks for desirability values for indications of goal fulllment, assessment of predened optimization criteria, and consideration of standard errors for measurement precision.The specic details and goals of the experiment have a signicant impact on interpretation of the results, and the features are utilized to delve deeper into the results and potentially identify optimal conditions based on dened criteria.Table 3 gives the outcomes of the 60th optimality run that is close to the 20 wt% PALF and 6 wt% FA, which gives relatively better mechanical characteristics, while Fig. 9 gives the results of the optimal trial run and the standard error.
The pilot set of Taguchi analysis and response surface methodology (RSM) was accomplished for the tensile strength to ascertain the outcomes of the optimality test, i.e., to analyze the impact of wt% of PALF and FA on the characteristics of the composites.The response tables for signal to noise (SN) ratios and means are given in Tables 4 and 5, respectively, and plots of the main effects are represented in Fig. 10 and 11, respectively.
From the response tables and main effects plot, it is evident that level 2 gives the maximum UTS in MPa for the "larger is better" ratio for SN ratios and the main effects plot with the wt% of FA being ranked 1, as the major contributor to the UTS, followed by wt% of PALF.
Further, the RSM was accomplished in Design-Expert soware to ascertain the optimality with reference to the wt% of PALF and FA for UTS in MPa for the composites.Fig. 12 and 13 give the surface plot and 3D contour plot for the different design points for varying wt% of PALF and FA.From the plots, it is evident that the maximum UTS represented by red-coloured zones is observed for the range of 6 wt% to 6.5 wt% for FA ller, and 20 wt% to 22 wt% for PALF reinforcements.The predicted vs. actual plots for the UTS (MPa) are in close correlation with each other, as shown in Fig. 14.
Table 6  Table 7 gives the t statistics, where the predicted R 2 of 0.5672 is not as close to the adjusted R 2 of 0.8552 as one might normally expect; i.e. the difference is more than 0.2.This may The regression equation obtained from the t statistics for UTS (MPa) obtained from RSM is given by eqn (2).
where A is coded for PALF in wt%, while B is coded for y ash in wt%.
A conrmation test was accomplished to ascertain the authenticity of the model and its predictions with the outcomes.Table 8 gives the results of the conrmation test.
From the table, it is evident that the predicted UTS, up to the fourth decimal is in close agreement with the experimental UTS, and the RSM model evolved using Design-Expert is thus validated with the optimality test results and the Taguchi model evolved using Minitab Soware.

Comparison with neat epoxy, neat epoxy + F6 and neat epoxy + P20
The investigation explored epoxy composites reinforced with PALF and FA as an eco-friendly alternative to conventional synthetic composites, noting the inherent strength and stiffness of PALF and the potential of FA as a composite ller.The study compared the mechanical properties of various epoxy composites with differing compositions of FA and PALF, including neat epoxy variants for reference.The results indicated that the P20F6 composite exhibited the highest overall performance, displaying superior exural strength (165.3MPa), exural modulus (4.6 GPa), and impact strength (33.56 kJ m −2 ).Although the P10F6 and P30F6 composites also performed well, P20F6 showed slightly better results.All the composites showed enhanced mechanical properties compared to neat epoxy, underscoring the effectiveness of PALF and FA as reinforcing materials.The choice of optimal reinforcement-ller combinations depends on specic application requirements and desired trade-offs between strength, stiffness, and impact resistance.Further optimization and characterization may be necessary for the precise adjustment of composite characteristics for specic technical applications.The optimal wt% of bre and ller, viz., the P20F6 composite, demonstrates the best overall performance, making it suitable for applications prioritizing these properties.Further, the optimality Fig. 10 Main effects plot for SN ratios for UTS (MPa).
test concluded that 20.837 (approx.21) wt% PALF and 6.46374 (approx.6.5) wt% FA closely predicted outcomes in close correlation with the experimental ndings, further reducing the value gradient to obtain the optimal proportion of reinforcement and ller for the composite.

Water absorption
The water absorption readings were closely monitored for an interval of 24 hours for a duration of 5 days, and the data is recorded and tabulated in Table 9.A duration of 5 days was considered as the initial set of pilot experiments, revealing that water absorption tends to become almost constant beyond 5 days.The provided data outlines water absorption percentages for various specimens.Across specimens such as P10F3, P20F3, and P30F3, an increase in the wt% of FA corresponds to a general decrease in water absorption, indicative of the ller effect that diminishes overall material porosity.This trend persists in specimens like P10F6, P20F6, and P30F6, where a higher FA content results in a decline in water absorption, attributed to the lling effect reducing available void spaces.Similarly, the pattern continues in P10F9, P20F9, and P30F9, where elevated FA content correlates with reduced water absorption due to the lling effect and overall porosity reduction.Comparative analysis with neat epoxy, neat epoxy + F6, and neat epoxy + P20 reveals that the addition of PALF generally increases water absorption compared to neat epoxy, possibly due to the hydrophilic nature of these bres.In general, specimens with higher pineapple bre content exhibit heightened water absorption, potentially owing to the introduction of additional porosity or hydrophilic characteristics.Conversely, the incorporation of FA tends to diminish water absorption, indicating its potential role in reducing porosity and enhancing water resistance.Further, the water absorption also decreased over a period of ve days owing to saturation of the affinity of the bres to absorb water, and also the micro-coring and closure of the void spaces and micro-gaps between the bres and the matrix brought about by the FA ller.In summary, the water absorption trends reect the intricate interplay between pineapple bre and FA, where pineapple bre tends to enhance water absorption, and FA exhibits a lling effect, leading to decreased water absorption, with specic outcomes contingent on the wt% of these additives in the epoxy matrix.Fig. 15 gives a graphical representation of the % water absorption for different samples with error bars over a duration of 5 days for every 24 h interval.The results of the present work are interpreted using the ndings of M. K. Kumar et al.The water absorption test involved immersing the samples in distilled water at room temperature, with specimen weights measured and recorded every 24 hours.Following 432 hours of water immersion, saturation in water absorption and thickness swelling were noted in all composite samples.In comparison to neat epoxy, the inclusion of reinforcements led to an increase in moisture absorption.The composite with optimum wt% of natural reinforcement and ller component demonstrated a noteworthy reduction in water absorption, which was ascribed to consistent mixing and enhanced bonding between the reinforcements and the matrix. 58

Scanning electron microscopy (SEM)
The morphological investigation of the P20F6 composite specimen was performed utilizing a TESCAN VEGA 3 machine, with an examining voltage of 10 kV.The SEM images yielded a complete portrayal of the microstructure of the composite The SEM images give substantial information on the impact of FA on fortication between the framework and the reinforcements.Moreover, it is observed that fracture proliferation and cracking were attributed to the laments from the lattice owing to laminar debonding, as well as isolation of the grid by pulling out strands.Fig. 16, 17 and 18 elucidate the morphology of the composite with magnications of 100×, 350×, and 500×,    respectively.These pictures successfully portray two critical components: the bre pullout and the homogeneous dissemination of FA in the matrix network.

Conclusions
The study demonstrated notable enhancements in PALFreinforced epoxy composites by the inclusion of FA ller for biomedical applications.
The tensile strength enhanced with the incorporation of 6 wt% FA surpassed that of neat epoxy by 65.3%.Nevertheless, the tensile strength exhibited a progressive decline beyond this threshold.
Flexural strength was signicantly improved by including FA, resulting in a peak enhancement of 31.9% at 6 wt%.However, a further increase in FA content led to a minor reduction in exural strength.
Signicant enhancements in impact strength were seen for the addition of 20 wt% PALF and 9 wt% FA, resulting in a stunning 74.18% increase compared to the original epoxy.
An optimality test conducted with 20.837 wt% PALF and 6.46374 wt% FA predicted results that closely matched the experimental data.
The Taguchi results revealed that level 2, viz., 6 wt% of FA ranked 1 (higher delta value) and 20 wt% of PALF, yield the maximum UTS from the response tables for SN ratios and means based on the "larger is better" condition.
Optimality is further validated based on the prediction equations obtained from RSM model evolved using Design-Expert.The % error between the experimental outcomes and predictions for conrmation experiments for UTS is less than 2%, which conrms the RSM model and justies the results of the optimality test.
The investigation demonstrated a decline in water absorption when FA was added, indicating enhanced water resistance in the composites.The water absorption of the P10F6 composite was found to be at a minimum of 1.1% on the h day, which is nearly equivalent to the water absorption rate of pure epoxy.
Morphological analysis revealed that FA was uniformly dispersed within the epoxy matrix, indicating strong interfacial bonding between PALF and epoxy.This uniform dispersion signicantly contributed to the enhancement of mechanical properties, improved load transfer, and increased resistance to crack propagation.
In summary, the study highlights the use of FA as an environmentally friendly ller, which improves the mechanical properties and decreases water absorption in epoxy composites reinforced with PALF.This environmentally conscious technique promotes the use of agricultural waste for economically feasible and sustainable composite materials that are suited for biomedical applications.It provides insights into the durability and stability of these materials in biological environments.

Fig. 3
Fig. 3 Photograph of the composite laminate fabricated in the present work.

Fig. 15 %
Fig. 15 % water absorption for different samples for every 24 h interval over a period of 5 days.

Table 1
Wt% of constituents for different specimen designations

Table 2
Mechanical properties of pineapple leaf fibre and FA reinforced epoxy composites gives the ANOVA table, where the F-value of the model of 10.45 clearly shows that the model is signicant.There is only a 4.09% chance that an F-value this large could occur due to noise.Further, P-values <0.05 indicate that the model terms are signicant.In this case B and B 2 are signicant model terms.P-values >0.1 indicate that the model terms are not signicant.If there are many insignicant model terms (not counting those required to support the hierarchy), model reduction may improve your model.

Table 3
Outcomes of the 60th optimality trial run block effect or a possible problem with the model.The critical factors for t statistics to consider are model reduction, response transformation, outliers, etc.All empirical models are tested by doing conrmation runs.Adeq precision measures the signal to noise ratio.A ratio greater than 4 is desirable.The ratio of 8.719 indicates an adequate signal.This model can be used to navigate the design space.
Fig. 9 Results of the 60th optimality trial run and the standard error.© 2024 The Author(s).Published by the Royal Society of Chemistry RSC Adv., 2024, 14, 14680-14696 | 14687 Paper RSC Advances indicate a large

Table 4
Response table for SN ratios for UTS (MPa)

Table 5
Response table for means for UTS (MPa)

Table 6
ANOVA table for UTS (MPa) from RSM

Table 7
Fit statistics for UTS (MPa) from RSM © 2024 The Author(s).Published by the Royal Society of Chemistry RSC Adv., 2024, 14, 14680-14696 | 14691 Paper RSC Advances material, explaining the dispersion and direction of PALF and FA inside the epoxy framework.